Price, Sharpness, very smooth bokeh, good construction, great for products and portraits. I found it to be very much equivalent to any good Canon L lenses.

Cons:

This lens is suberb, and should have HSM. It's not really needed for the Macro side of work, with products or food which stand still on the table, but since it's a great lens, and I also use it for fashion and portraits, I'd like it to have USM/HSM focus speed.

I purchased this lens, as a complementary lens for shooting food, and also, as a macro lens for still and jewelry shots. Well, after researching, I went to a store, and compared it to the Canon Macro 60mm f2.8 USM (EF-S) and Sigma 50mm Macro f2.8, and it won, hands down. The only close competitor on this comparison was the 60mm Canon EF-S, but being EF-S, it's restricted on a long term use.

But I was surprised to see this lens, not only performs beyond my expectations as a lens for food and still photos, but it also excels on portraits and fashion. The only downside, is that it lacks high speed autofocus, but it would add too much to the price tag. I honestly have no complaints, and I can feel the quality diference on my work already.

And I have handled some L quality lenses before. 70-200L f2.8 non-IS, 24-70L f2.8 and 16-35L f2.8, and this lens is pretty much on their league. Ok, it's a fixed prime lens, but from the idea I have been seeded around Sigma, that their quality is lower than Canon's L glass, I have to say, I'm mesmerized by the output I get from the investment. I guess I'll stick with this lens as one of my main work lenses for years to come.